mineral

Tumbled purple chalcedony or amethyst

Microcrystalline quartz (SiO₂), possibly amethyst variety

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent purple to lavender, vitreous/waxy luster, no visible cleavage, conchoidal fracture, trigonal quartz structure. The smooth rounded surface indicates tumbling and polishing.

Identified August 22, 2026More mineral →

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Physical properties

Formation & geological history

Quartz formed from silica-rich fluids filling cavities in volcanic rocks; purple color in amethyst commonly results from iron impurities and irradiation. Formation ages vary widely, commonly Paleozoic to Cenozoic.

Uses & applications

Used for inexpensive jewelry, cabochons, carvings, and decorative stones. Small tumbled pieces generally have modest collecting value.

Geological facts

The image is not sharp enough to distinguish amethyst, purple chalcedony, or dyed quartz confidently; visible internal banding or crystal faces would help.

Field identification & locations

Identify with a glass-scratching test only cautiously, since quartz scratches glass; quartz has no cleavage and feels relatively hard. Common sources include Brazil, Uruguay, Mexico, Madagascar, and the United States.